Grinding machine for shaping surfaces



7 Sheets-Sheet 2 C. J. GREEN GRINDING "MACHINE FOR SHAPING SURFACES Dec.1, 1953 Filed Dec.

fizz/altar Cuuaw-vcr: J. GREEN flccorney Dec. 1, 1953 c. J. GREEN ,660,36

GRINDING MACHINE FOR SHAPING SURFACES Filed Dec. 13, 1951 '7Sheets-Sheet 3 I Inventor 4 CLARENCE J GEEEN Dec. 1, 1953 c. J. GREEN2,660,836

GRINDING MACHINE FOR SHAPING SURFACES Filed Dec. 13, 1951 '7Sheets-Sheet 4 Inventor- CLARENCE J 6EN 255 10% fltcorney Dec. 1, 1953C. J. GREEN GRINDING MACHINE FOR SHAPING SURFACES 7 sheets-sheet 5 FiledDec. 13, 1951 M W @J n MN 6 5 w u c a W N v H I J M w W M mwj 3m 1|||lwmm NR km on .mt/ H n i ii um m m m km m m QM QM Dec. 1, 1953 c. J.GREEN I GRINDING MACHINE FOR SHAPING SURFACES 7 Sheets-Sheet 6 FiledDec. 13, 1951 f @i 546a J RE fltarney Dec. 1, 1953 c, J, GREEN 2,660,836

I GRINDING MACHINE FOR SHAPING SURFACES Filed Dec. 15, 1951 7Sheets-Sheet '7 fizz/smear CLARENCE J GEEEN Patented Dec. 1, 1953GRINDING MACHINE FOR SHAPING SURFACES Clarence J. Green, Worcester,Mass., assignor to Norton Company, Worcester, Mass, at corporation ofMassachusetts Application December 13, 1951, Serial No. 261,493

43 Claims. 1

This invention relates to the shaping, asby grinding or other suitablemeans for cutting or removing metal, of surfaces such as the back orconvex face of a turbine or like blade where that surface, whilestraight line faired, is, geometrically speaking, generated by themovement of a straight line whose ends move along respectively differentcurved paths of different and varying relative radii or radial distancesfrom a given axis and at varying relative instantaneous rates.

One of the objects of this invention is to provide a practical anddependable method and apparatus for efficiently producing surfaces ofthe above-mentioned character in objects, usually made of metal, such asturbine blades. Another object is to provide a method and apparatus ofthe just-mentioned character capable of shaping surfaces in sucharticles uniformly and in a manner dependably to achieve quantityproduction of such objects. Another object is to provide a simple andpractical apparatus for facilitating carrying on of the just-statedmethod;

Another object is to provide a grinding apparatus for producing inobjects such as turbine blades so-called convex surfaces of theabovementioned peculiar characteristic of conformation. Another objectis to provide such a grinding machine constructed and operated toproduce and uniformly reproduce such surfaces in such objects in areliable and efficient manner to facilitate production of such articlesrapidly and thus lend itself to quantity production thereof.

Another object is to provide devices and mechanisms in the form ofindividual units or subunits for mounting and controlling the object orobjects in which the above-mentioned surface is to be formed, soconstructed and arranged that they are speedily and readily adapted orattachable to certain known forms of metal-removing machines such ascertain types of grinding machines, thus readily converting the latterfor production of the above-mentioned peculiar surfaces in articles suchas turbineblades.

Another object is to provide: apparatus of the above-mentioned characterthatpwill have, a substantial range of flexibility of arrangement orconstruction or adjustment to meet the, varying requirements met with inthe production of articles of the above-mentioned nature, particularlyturbine blades, wherein, as for different stages or different turbinecapacities. a substantial range of dimensionally different articles haveto be produced though all of them have a surface of the above-mentionedpeculiar geometric characteristics, with even those characteristicsvarying or changing according to circumstances.

Other objects will be in part obvious or in part pointed outhereinafter.

The invention accordingly consists in the features ofv construction,combinations of elements, arrangement of parts, and in the several stepsand relation and order of, each of the same to one or more of theothers, all as will be illustratively described herein and the scope ofthe application of which will be indicated in the following claims.

In the accompanying drawings in which is illustratively shown apreferred embodiment of the mechanical features of this invention and inwhich similar reference charactersrefer to similar parts throughout theseveral views,

Figure 1 is a small-scale front elevation of the machine for producing,in work-pieces such as turbine blades, surfaces of the above-describedcharacteristics;

Figure 2 is a small-scale diagrammatic representation, in elevation, ofa turbine blade blank on which the above-mentioned surface is to beformed;

Figure 3 is a diagrammatic perspective View of only the blade portion ofthe blank of Figure 2, to indicate diagrammatically some of thegeometric peculiarities of the surface to be formed;

Figure 4 shows diagrammatically the external and internal contours ofthe blade as seen from the right in Figure 3 and, moreparticularly, isintended to show the curved line along which the right-hand end, as seenin Figure 3, of the straight-line generator moves;

Figure 5 is a View similar to that of Figure 4, being a projection ofthe left-hand end of the blade of Figure 3, to show diagrammatically thedifferent curvature along which the left-hand end, as seen in Figure 3,of the straight-linegenerator of the convex surface moves;

Figure 6 is a large-scale horizontal sectional view as seen along theline 66. of Figure 1 showing certain features of head stock and tailstock units, with the work-piece supported thereby, in operativerelation to the grinding Wheel, being in the form, respectively, of aleft-hand form control and a right-hand form control for shifting,respectively differently, the left-hand and righthand ends of-theWork-piece;

Figure 7 is a horizontal large-scale sectional view as seen along theline l---? of Figure 1 showing certain features of construction of apowerdrive head or unit, for driving the controls of the head stock andtail stock units;

Figure 8 is a large-scale end elevation of the power-drive head or unitas seen from the left in Figure 1;

Figure 9 is a large-scale plan view of the tail 3 stock control unit asseen along the line 99 of Figure 1;

Figure 10 is a large-scale vertical sectional view through the tailstock control unit as seen along the line ii5 of Figures 1, 6, and 9;

Figure 11 is a fragmentary vertical sectional view of a roller mountingas seen along the line i I-l I of Figure 10;

Figure 12 is a transverse vertical sectional view, on a reduced scale,through the grinding wheel slide and wheel feeding mechanism,substantially as seen along the line i2- I2 of Figure 1, certain partsbeing omitted;

Figure 13 is a fragmentary elevation, on a larger scale, as detachedfrom Figure 6, showing the work-holder or arbor which supports twowork-pieces or blades and which is carried in the controllably displacedsupports provided by the left-hand and right-hand control units orstocks;

Figure 14 is an elevation thereof as seen along the line I l-I4 ofFigures 13 and 6;

Figure 15 is an end elevation thereof as seen from the right in Figure13 Figure 16 is a diagrammatic representation of the relationshipsbetween various parts of the apparatus and the work-piece showing therelative positions of the parts at the commencement of a contourgrinding operation and the workpiece; and

Figure 17 is a diagrammatic representation like that of Figure 16 butshowing the relative positions of the various parts at the conclusion ofa contour grinding operation on the work-piece.

As conducive to a clearer understanding of certain features of thisinvention, reference might first be made to Figures 2-5; in Figure 2 Ihave diagrammatically indicated, and designated as a whole by thereference character T, a turbine blade member comprising a blade B whoseexternal and generally convex face is to be shaped, having integrallyformed with it and at its respective ends block-like elements A and Cboth of which may be given any needed or desired conformationappropriate to serve as a means for mounting the blade unit T in theturbine structure and which when so conformed, as by machining orgrinding or the like, serve as engageable means by which the blade unitmay be supported and positioned for machining, grinding, or otherwiseshaping the surfaces of the blade B itself; sometimes only one of suchblock-like end elements is required for mounting the blade unit in theturbine structure, and in such case the other is simply cut oif uponcompletion of the blade-surface shaping operations. The blade B,diagrammatically shown on a larger scale in Figure 3, is of curvedcross-section and may be of varying thickness. It has an inner curvedface IF which may be generally considered as concave and which may beshaped in any desired way. Its external face F, in general convex andwhich is to be shaped according to this invention, is straight linefaired, being generated by movement of a straight line with its endsmoving along two curved paths of diiferent and varying relative radii orradial distances from a given axis and at varying relative instantaneousrates. If the surface is thus regarded as being made up of straightlines, the latter are thus never parallel to each other though portionsof the surface, according to design or circumstances, may be trulycylindrical or frusto-conical where, throughout two correspondingportions of the two paths through which the ends of the straight 4 linemove, those two portions are equal or geometrically similar and therespective rates of movement therealong of the ends of the generatingline are the same.

In Figure 3 the lines E are intended diagrammatically to represent notall but only successive positions of the generating straight line so asto indicate this peculiar condition of straight line fairing where thestraight lines are not parallel in some regions and may be parallel inother regions. In Figure 3 the curved paths along which the respectiveleft-hand and right-hand ends of the line E move are indicated at G andH, each beginning at the leading edge 20 and each terminating at thetrailing edge 2i of the blade B. At the leading edge 28 the straightlineend of the surface F may merge, in suitable curvature, into the insideface IF of the blade, and at the trailing edge 2! the other straightlineterminus of the face F may similarly merge, but usually at a lesserradius of curvature, into the inside face IF, or the two faces maysimply intersect each other where it is desired at the trailing edge tomaterially taper off the thickness of the blade. While in Figure 3 therespectively different paths G and H are indicated in diagrammaticperspective, they are shown in elevation or in development in Figures 5and 4, respectively, all three figures, as shown, being related to adatum line or axis O-X with relation to which, also, the faces,surfaces, or other configurations needed for the block-like end elementsA and C are formed so that by suitably engaging and positioning theparts or faces of the end elements A and C, as in a work-holder W(Figure 6), the axis O-X may be fixedly positioned in relation to thework-holder itself.

As is later pointed out, the work-holder W, which is rotatable, isconstructed to have an axis of rotation, and by the just-describedrelation ships of the parts of the blade end elements A and C withrespect to the axis QX, the blade member T may be readily located andsecured in the work-holder itself, with the axis O-X coincident with theaxis about which the workholder is constructed to rotate.

The curved lines or paths G and H represent the section contours for theexternal face of the blade B at the respective ends of the latter and,as above indicated, the surface F is to be determined by straight linesjoining the contour section lines G and H even though, in part or inwhole (according to design or circumstances), successive lines are notparallel to each other and the angularities between successive lines andthe radial distances of their respective ends from the axis O-X differat the left-hand end and the right-hand end of the blade B and may sodiffer in uniform increments or even in irregular increments per unit oflength along the contour sections G and H.

Illustratively, referring to Figures 4 and 5, the

surface F is to have an upper portion F of the same radius 1' throughoutan angle a: at the righthand end and throughout the angle 0: at thelefthand end, with angle 13 greater than angle a: and with the verticalplane through the bisectors of these two angles coincident with the axisOX, the center from which the radius r is taken being in that verticalplane but spaced upwardly from the axis O-X. The portions of the sectioncontours G and H subtended by the angles x and 0:, respectively, maythus each be said to have a point of maximum vertical displacement fromthe axis O--X, and the line joining these two points, being in theabove-mentioned vertical plane, is parallel to the axis O-X, but toeither side of that vertical plane the surface portion F falls off atsuccessively shorter distances from the axis OX but throughout a greaterangle 5-2 at the left-hand end than the angle a: at the right-hand end.The over-all vertical dimension of the section contour H at the rightend, represented by the reference character 2 is greater than thecorresponding dimension 2 at the left end, and the spaciir y from theabove-mentioned vertical plane of the lower terminus of the sectioncontour H at the right end is greater than the correspondingdisplacement y of the lower terminus (trailing edge) of the sectioncontour G at the left end because of the desired straight line iairedportion F of the external face F of the blade 35. Throughout the portion1 therefore the distances in radial directions from the section contoursG and H to the axis OX change, not only throughout the correspondingportions of the section contour but also may change dinerently or at adifierent rate in the one section contour the change in the other, allin turn modified by the fact that the peripheral extent of the surfaceportion F at the right end section contour is greater than that at theleft end section contour G. It is this peculiar type of straight linefaired surface which the blade member T of Figure 2, usually a forging,is to be given after the block-like end elements A and C thereof havehad suitable parts or surfaces thereof machined or otherwise finished ingeometric and dimensional relation to the axis O-X.

In producing the above-described illustrative geometric straight linefaired surface I prefer to remove metal from the outer convex portionsof the blade B by a suitable cutting tool, preferably by grinding,utilizing preferably a peripherally acting grinding wheel whoseperipheral face can be trued to true cylindrical form, with eachstraight-line element of the resultant cylindrical grinding wheel faceparallel to the axis of rotation of the grinding wheel; such a grindingwheel is indicated in the drawings (Figures 1, 6, and 12) by thereference character 22 and, as indicated in Figure 6, it is preferredthat the axial dimension of the grinding wheel 22 be substantially thesame as the length in an axial i" grinding wheel marks in the surface ofthe worlrpiece. In constructing the apparatus I prefer to employ anumber or elements of any suitable known or standard type of grindingmachine, such as that disclosed in Patent No. 2,522,485 to Silven etal., issued September 12, 1950, to which reference may be had fordetails of construction and of operation and control of such selectedelements. The latter include a base 23 provided with a longitudinallyextending V-way 2t and a companion flat way 25 (see Figure 12) by whicha longitudinally slidable or reciprocable table 28 is supported andguided for movement; since, for purposes of the present invention, thetable 25 need not partake of power-driven reciprocation or travel, thecorresponding table u I GU drives and controls of the Silv'en patent maybe omitted or simply not utilized and use can be made only of the manualtraverse wheel 2'? (Fig ure '1) which is operatively connected inconvention'al manner to rotate a gear mechanism which meshes with a rackbar 25 (Figure 12) that extends longitudinally of and depends from theunderside of the table 26. Any suitable or conventional means may beemployed to lock the table 26 in selected position.

The grinding wheel 22 is carried on one end of a spindle 39 (Figure 12)mounted in suitable bearings in a, grinding wheel slide 3i (Figures 1and 12) which is slidably mounted in usual manner one pair of rearwardlyand hence transversely extending fiat and V-ways 29 so that the grindingwheel is movable toward and away from the longitudinal table 26 (Figure12) or toward and away from the observer viewing Figure 1, the axis ofthe grinding wheel spindle 353 being parallel to the line oflongitudinal traverse of the table 26. The wheel spindle so ispreferably driven by an electric motor 32 (Figure 1) carried by thewheel slide 3i by driving V-belts 33 connecting motor pulley 34 withpulley 35 which is carried by the other end of wheel spindle 30.

Wheel slide 38 may be fed toward or away from the front table 26 by afeed screw 35 (Figure 12) journalled in anti-friction bearings 31 and38. The wheel slide 3! is provided with a depending half-nut as whichmeshes with the feed screw 36 and accordingly the wheel slide 3i and itsgrinding wheel 22 partake of movement toward or away from the fronttable 26 if the feed screw 36 is bodily moved (hydraulically, forexample) or if the feed screw 36 is given a rotary movement, as, forexample, by means of a manual operable feed wheel ii (Figures 1 and i2)mounted at the front of the machine base 23 and pro vided with suitabledriving connections with the feed screw 35. The means for hydraulicallyacturating-and controlling the wheel slide 3! and the mechanismconnecting the feed screw 3% with the hand wheel 4| may be substantiallythe same as those shown and described in the above-mentioned Silvenpatent.

On the table 26 I mount, preferably detachably, suitable subunits forsupporting and controlling the arbor or work-holder in which one or moreblade elements T (Figure 2) are secured; these subunits are preferablyso constructed that they may replace, or be replaced by, other subunitsor heads constructed to effect other kinds and types of grindingoperations by the grinding wheel 22, and such subunits may be directlyor indirectly supported by the table 25. For purposes of illustrationand not by way of limitation, the table it may support, substantiallythroughout its length, a swivel table 52 (Figure 1) by which, as isusual in the case of certain grinding operations for such other subunitsor heads, the alignment of such other heads relative to the grindinwheel axis or relative to the longitudinal path of travel of the tableis may be given an angularity or inclination about a vertical axis, anaxis usually provided by a suitable pivotal connection between the twotables in the form, for example, of a heavy cylindrical block or studindicated at ts in Figure 1, there being clamping devices 44 at therespective ends of the two tables to fix the swivel table ii in thedesired relation to the sliding table 2%. For purposes of the presentinvention, the swivel table 62, if employed and where the heads orsubunits of my invention are not secured directly to the sliding table25, is fixed in a position of zero angularity relative to the slidetable 25; its longitudinally extending guide surfaces, clamping grooves,or clamping angularities by which the subunits are secured theretotherefore extend parallel to the grinding wheel axis and parallel to theline of longitudinal traverse of the slide table 25. As shown in Figure10, the upper face 32 of table :32 is inclined downwardly and toward threar of the machine as the latter is viewed in Figure l, and its frontface 42 is machined at an acute angle to form a V-shaped aligning guidewith which the various heads or subunits interfit in that they havecorresponding V-shaped recesses or slideways; at its rear longitudinaledge the table 32 is also given a V-shape but of an angle so thatclamping elements 65, controlled by clamping screws 56 and carried bythe various subunits, may coact therewith to fasten the various heads orsubunits in selected position lengthwise of the table as well as to fixthem in accurate alignment with each other.

In the preferred embodiment of my invention, to the table 42 I secureand align with each other, as just described, three heads or subunitsgenerally indicated by the reference characters 5|, 52, and 53comprising, respectively, a powerdrive head, a head stock control unit,and a tail stock control unit, of which the latter two are spaced apartlengthwise of the machine to provide for the entry therebetween of thecutting tool or grinding wheel 22 and to provide ample space torotatably support therebetween the arbor or work-holder generallyindicated by the reference character W, all as is better shown in planin Figure 6 and in front elevation in Figure 1. In the illustrativeembodiment the work-holder W is constructed to fixedly secure inposition and on two opposite sides thereof two blade members T (Figure5) in a manner to bring the axes 0-2! (Figure 3) thereof intocoincidence with each other and with the axis, hereinafter alsodesignated OX, of the work-holder W, th axis of the latter bein fixed bythe provision of journal boxes JL and JR in respective ends of thework-holder W which are provided with bearing recesses that are ofspherical contour or section, presenting bearing surfaces which aresubstantially zones of spheres whose axes are aligned or coincident;they are preferably of substantial radius, as is better indicated inFigures 13 and 142, to provide substantial areas of bearing surface forthe reception, respectively, of the ball or spherical 55 and 55 of thetapered centers CL and CR (Figure 6) carried, respectively, by the headstock control unit 52 and the tail stock control unit 53.

Journal boxes JL and JR may be made of any suitable material havingsuitable hardness or wear resistance and hence long life, and as shownin Figures 6 and 13-15 they are set and fixed in suitable recesses inthe respective ends of the work holder W. Their spherical-sectionedhearing surfaces, by the line joining the aligned axes of the spheres ofwhich they are zonal sections, fix and determine an axis of rotationalsupport for the work-holder W, and in securing the blade members T, T tothe latter the axes O-X of the blade members are brought intocoincidence with each other and with that work-holder axis. As indicatedin broken lines in Figures 6- and 13, thes journal boxes JL and JR, atthe respective bottoms of their bearing recesses, are provided withstraight cylindrical recesses of lesser radius,

as by drilling, to accommodate or receive particles of foreign matter soas not to interfere with the spherical-surface contacts which theballlike center ends 54 and 55 are to make with the journal bearingsurfaces.

The resultant ball and socket connection and support at each end of thework-holder W permits precise shifting, and control of shifting, of eachend of the axis O--X of the work-holder W by controlled related butindependent shifting of the centers CL and CR and hence of theirrespective ball ends 54 and 55, in all directions transversely of thegeneral line of the axis of the work-holder W, in the preferred mannerlater described in detail and in relation to the grinding line ofcontact GL of the grinding wheel 22, that being, as later explained,always that straight line of the cylindrical face of the grinding wheelthat falls in the same horizontal plane with the axis of th grindingwheel spindle 3B, the head stock and tail stock units 52 and 53 beingconstructed to present the universally movable centers CL and CR, whilein general axial juxtaposition to each other as shown in Figure 6, at aheight that is in the region of the horizontal plane through thegrinding wheel axis and the grinding wheel contact line GL. These balland socket supports and connections permit the coincident axes of thework-holder W and of the supported blade members T to be given a widerange of tilting both horizontally and vertically, in the same ordifierent degrees as Well as directions at the respective ends thereof,to bring any straight fair line to be ground in the blades B always incoincidence with th horizontal straight grinding line of the grindingwheel 22; at the grinding line GL the grinding wheel always cuts astraight horizontal line in the work-piece or blade B, and by moving theball-ended centers CL and CR independently but in relation to each otherwhile slowly rotating the work-holder and blade, the common axis OX isshiftable and tiltable, relative to the fixed horizontal grinding lineGL of the grinding line GL, so as to successively present to thegrinding line elemental portions of the blade B, such as the elements Eof Figure 3, to produce the straight line faired face F. Depending uponthe desired character of the face F, of which one illustration isdescribed above, the axis O--X of the work-holder W may thus be made toassume a wide variety of relationships to the fixed horizontal straightgrinding line GL; one end of that axis may be higher or lower than theother and displaced inwardly toward the grinding wheel more or less thanthe other, in which case it is never parallel to the grinding line GLwhile at other times it might be parallel to the grinding line, and thenagain it might fall in the same horizontal plane with the grinding lineGL but be tilted to the latter, or it might fall in a vertical planeparallel to the horizontal grinding line but be tilted to thehorizontal. By coordinating physical displacement or movement of theball-ended centers CL and CR, preferably by displacing each alwaysparallel to itself, and in coordinated and related closed paths ofmovement for the ball ends, the axis O-X of the workholder and of thetwo accuratelydiametrically opposed blade members T, T may be given suchshifts and inclinations relative to the grinding line GL as have justbeen described and in such sequences as to be capable of producing awide variety of straight line faired surfaces having peculiarities ofsuccessive curvatures and angu- 671! provided with bottom walls thatare. inclined and shaped to interfit with and be clamped to. the table42 as earlier above described and as shown in Figure 10 in connectionwith the tail stool; unit -3, being thereby accurately aligned and alsoadjustably positionable in relation to each other and lengthwise of the,tablev 42. They have upstanding vertical walls, some of which are brokenaway or provided. with suitable. open.- ings, and each is provided witha removable top cover plate and 59 (Figure, 1). As shown in Figure 6,the ball-ended centers CL and C3 are supported to project toward eachother through relatively large openings in the adjacent end Walls of theframe housings 5t and 51, thus providing ample clearance for freedom ofdisplacing movement of each center in all directions and preferablyalways parallel to itself. The left.- hand center CL is taper-fitted inusual manner into the right-hand end of a driven shaft 61} mounted fordisplacement in all directions parallel to itself, and the right-handcent-er CRis taper-fitted into the left-hand end of an axially slidablesleeve 5i which is also supported for displacting movement in alldirections parallel to itself. The supports for the shaft 66 and thesleeve 3!, for displacing movements, are substantially identicallyconstructed and it will sufflee to describe in detail the supportingstructure for one of them, namely, the one associated with the tailstock control unit 53, better shown in Figures 9 and 10. In the main,each support comprises two pivotally connected carrier links which, forthe tail stool: unit, are shown inv Figures 9 and 10 at 2 and 63. Link62 is preferably in the form of a relatively heavy casting ofsubstantial length and breadth (see Figure v9) and extends in a generalhorizontal direction- (Figure lil) within and. across the upper portionof the frame housing 5?, just under the cover plate 59,

and at its front end ispivotally supported by the frame housing at toswing about an axis parallel to the interfitting guideways and guides ofthe frame housing and the table 4.2 (Figure. 1.0.) that axis beingtherefore parallel to the grinding line GL of the wheel 22 and alsoparallel tothe grinding wheel spindle axis. The pivotal support ispreferably by way of bearings of substantial, axial spacing, thus toresist the reaction of stresses. tending to twist the pivoting axis outof the justdescribed parallelism, and may be provided and constructed asis better shownin Figure 9, wherein the forward end of the broad link 52is bored. out as at with the edge walls of the-bore slotted as is bettershown at 5.5 in Figure 10, opposed parts of the slotted bore wall beingprovided with clamping screws 65 to draw them toward each other. Intoopposite ends of the slit bore 3, Studshafts iii and iii; (Figure 9) areinserted whichat their respective outer ends carry and havesecured theinner races of combined radial and thrust roller bearings ii and t2, theouter races oi which are seated and secured in counterbores it andrespectively formed in the opposite end walls of they frame housing 57.Th two stud,

110. shafts; 61 and B8. are. or reduced diameter inter,- mediate theirends so as to provide, spaced clamp-.- a p rtions. that neatly fit he bre. 54*: an a located, as indicated in. Figure 9, in those-regions,where. the axially spaced clamping screws 56 are effective to stra n theslit o e Walls tow rd ach. other for. good clamp n ac on. Th s n ementinsures better accuracy of ali me of th stud shafts and the r d b r n s'i and t coaxially with t e bo 51 and Perm som d;- justrnent, oi thespacing between the endbearings ii, and i2, whose outer races are, heldagainst axial shift. by an ular flan s th l re. plates i5, and it thatclOSi over the outer ends of the end wall bores i3 and i4 and which aresecured to the end Walls in any suitable way, as by screws.

. From the. just-described pivotal support the carrier link 52 extends,toward the rear wall of the. frame housing 572' and it is bored out atits rear end, as at '57, with the axis of the bore parallel to the axisof bore 64 at the front end. The rear end wall of bore ii islongitudinally slit, as at 718. (Figure 10), the opposed slit wallportions being provided with clamping screws 89 (Figure 9) to clamp,coaxially with bore ll", two studshafts 8| and 82 received into the borefrom opposite. ends. thereof and of reduced diameter intermediate.their, ends for better precision of clamping; the, outer ends of studshafts Bl and82 have secured thereto theinner races of combined thrust.and radial roller bearings 83 and 8 which by this construction arev alsoof substantial axial, s aclng.

The outer races of the bearings 83. and. 8.4 are received in suitablebores and held and positioned by annularly flanged platesv 85 and 8t,respectively, formed in the parallel axially spaced up Wardly extendingarms 63 and 553 of the carrier link 63 which, is substantiallyel-shaped, the hori-. zontal or cross-bar portion of which is shown incross-section at, 63 in Figure 1c. The carrier link 63 extendsvertically and downwardly from the rear end of the horizontal carrierlink 62 (see Figure 10), and by the above-described pivotal connectionbetween the two, the axis, about which link or arm 63 can swing isparallel to the axis or" pivoting of the link 62.

The. downwardly extending and axially spaced arms 83 and 63 (Figureswand 6) are bored out to receive and have secured coaxially therein aheavy sleeve 8? whose axis is p iral-lel to the axis about which theupper end of the pendent link 53 pivots, and it is within this sleeve 6?that, the sleeve, BI- which carries thev ball-ended center CE isslidably but. ccaxially mounted.

By means of the pivotally connected carrier links 62 and, 63 theball-ended center CR and its, axis may be shifted in all directions, asviewed, in Figure 10, and for any such direction the pivotal support forthe horizontal link as, permitting up and down oscillation, supplies thevertical component and the pivotal connection between the pendent linkt3 and the horizontallinlr .6 2, per

11 blade members T, T (Figure 6) carried by the work-holder W.

In similar manner, a similar mounting for the shaft 60 (Figure 6) thatcarries the live center CL of the head stock control unit provides formovement of the ball-ended center CL and by controls later describedthat center is displaceable or movable in any desired path, also inrepeated cycles synchronized with the cyclic movement of the right-handcenter CR of the tail stock unit 53, with such dissimilarities in thetwo paths of movement of the centers, in each cycle, that the axis ofthe Work-holder and of the blade or blades is universally tiltable andshiftable, as earlier above described. Accordingly frame housing 56 ofthe head stock control unit 52 also has, extending horizontally andrearwardly, just underneath its top cover plate 58, a horizontal link 92constructed and pivotally mounted the same as the link 62 abovedescribed and pivotally supporting at its rear end a depending H-shapedlink 93 substantially the same as the above-de scribed link 63 withpivotal connections therebetween the same as earlier described; inFigure 6 are shown in section the bored-out axially spaced lower arms 93and 93 of the pendent link 93, and in the bores thereof are mounted andsecured bearing structures for rotatably supporting the shaft 60 andholding it against axial thrust, the supporting linkages insuring thatthe axis of shaft 60, when the'latter is displaced, moves parallel toitself and is always maintained parallel to the interfitting guidewaysbetween the frame housing 56 and the table 42 and hence parallel to thegrinding line GL of the grinding wheel as well as to the grinding wheelspindle axis, regardless of what position the head stock unit 52 isgiven lengthwise of the table 42.

The spaced bearing structures for the shaft 653 (Figure 6) compriseexternally tapered bearing sleeves or bushings 94 and 85, eachlongitudinally slotted as at 9t and 95", respectively received withinsleeve elements 96 and 9? which are internally tapered and relative towhich the slit bearing bushings 94 and 95 may be drawn axially, to theleft in Figure 6, to contract them, by the respective nuts 98 and 99threaded onto the external threaded portions of the bearing bushings 94and 95, respectively, and bearing against the respective left ends ofthe sleeves 96 and 97; in this manner play and wear may be compensatedfor and the desired axial relation of the shaft 60 consistentlymaintained.

Axial thrust to the left is taken up by a suitable thrust bearing whichmay comprise a ring-shaped bearing plate l! secured, as by pins, to therig-hhand end of the bearing sleeve element 95 and coacting with athrust collar "32 splined to the shaft 60, as at I03, and adjustablypositionable along the shaft, as by set screw Hi l, the left end ofcollar I02 being provided with a ring-shaped member 105 of good bearingmaterial for bearing engagement with the bearing face of the stationarythrust plate lfll. This construction permits initial determination ofthe axial position of the shaft 65 in its axially spaced bearings andalso provides for takeup of play or wear between the thrust bearingelements. Axial displacement of the shaft 60 to the right is preventedby a collar I01 which bears against the left end of the split bearingbushing 95, being set in position by a set screw I08 after setting ofthe thrust bearing structure ll-I02. The right end of the bearingstructure 95-9! is closed off by a ring plate 12 H8 secured to the part91 and provided with an oil retaining ring III as shown.

Provision is made for driving connection, always in fixed and invariablerelation, between the shaft 65 and the work-holder W, bearing in mindthat the blade element or elements T, T are assembled to the work-holderalways with the blade surface to be ground in fixed relation to thework-holder, because of the synchronization, with the rotary movement ofthe work-holder, of the independent but related controls for shiftingthe two supporting centers CL and CR. Such connection convenientlycomprises a collar H3 (Figure 6) splined or keyed to shaft 65, as at H4,and removably secured to the shaft by set screw I E5, the splined orkeyed connection l I i thus fixing the position of a dog which comprisesa shank H5 projecting from and axially adjustably secured in acylindrical bore or recess in the collar H3 and terminating in a ballend Ill (see also Figure 13) that is receivable in a slot H8 (Figure 14)in the left end of the arbor or work-holder W and tangentiallyengageable at diametrically opposite points in the ball end I I? by theinner ends of two screws I25 and I2! (Figure 14). These screws arecarried in axially aligned threaded holes in the opposed walls of theslot it which is wider than the diameter of the ball end H? so that byadjustably positioning the two screws to clamp the ball end I ll betweentheir inner ends, the desired angular relationship of the workholder Wand blade or blades carried thereby to other control parts synchronizedwith the rotary movement of the work-holder may be obtained. For speedand facility in the removal and replacement of the work-holder W, ofwhich any suitable number of identical ones to carry identical andidentically positioned blade members T may be employed successively inthe machine, each such work-holder has one of its screws, such as thescrew I20, provided with a lock nut I22 to look its inner balldog-engaging end in the selected position once and for all while theother screw l2l, which may have a finer thread, is provided with aknurled head I23 for quick and easy manual control to bring it intoengagement with the diametrically opposite point in the ballended dog orwhen a work-holder is mounted in position and to quickly disengage ittherefrom when the work-holder is to be removed for replacement byanother in which blades to be ground are already secured in fixedrelationships as above described.

The inner ends of the screws 20, l2i provide fiat parallel faces ofsubstantial area so that dogdriving connection with the Work-holder W isalways maintained without play or back-lash even though the axis ofwork-holder W is thrown out of coincidence with the axis of the drivingor live center CL at varying angles in all planes, as the two ball-endedcenters 54, 55 partake of relative universal displacements as abovementioned and under the controls later described.

In effect under these controls and according to the characteristics ofthe straight line faired surface to be ground, the work-holder W and itsaxis as determined by the center-engaging journal boxes -JL and JR.(Figure 6) and with which the blade axes are coincident, may be said towobble, its ends partaking of different degrees and directions ofmovement according as the supporting centers CL and CR are controllablydisplaced. As a result the projected distance between the bearingsurfaces of the journal boxes JL and JR becomes less as the departurefrom co- 13 axiality of the supporting ball centers 54v and 55 becomesgreater. Accordingly provision is made for automatically adjusting thespacing between the ball centers 51? and 55 in a general axial directionto this change in distance, and this is preferably accomplished bycausing the dead center CR in the tail stock control unit to axiallymove or follow up a lessening of that distance and to axially recedewhen that distance increases. As, above described, center CE is fixedlycarried in sleeve 6! which is slidable in the frame sleeve 87, therebeing provided two axially spaced bearings i2? and lit (Figure 6), fixedWithin the, ends of the stationary sleeve ill and slidably supportingthe inner sleeve 6! at its extreme ends. Since center CR need not,rotate, a splined connection ltd is provided between the two sleeves. Atits right-hand end sleeve 6| is counterbored to re.- ceive a helicalspring 13E whose outer end bears against a fixed part secured, forexample, to the outer end of the bored-out arm 83 of the pendent link63. Spring 53! is normally under compression and exerts a continuous butyieldable force urging the sleeve ti and center CR to the left in Figure6 and hence in the general direction toward the opposed center CL;thereby the two.

centers CL and CR are self-accommodating to what-ever changes in theirspacing is necessitated by the angular shifts of the work-holder Wrelative thereto, and the arbor W and its blade or blades T are assuredof dependable rotative support throughout their wobble.

Drive shaft B of the head stool; control unit and hence the work-holderW are rotated at a relatively low angular velocity, on the order of 20R. P. M., and in the preferred embodiment are driven at a constantangular velocity, in which case the controls for the relative universalshifts or displacements of the centers CL. and CR, synchronized with therotary movement and physical displacement of the blade to be ground, aremore conveniently correlated increment by increment of angular rotarymovement of the blade. The drive of shaft (iii and live center (Land thedrive of the shaft controls in the head stock and tail stock units arepreferably effected by the provision of the drive head or power unit 5iearlier above mentioned and better shown in Figures 1, 7, and 8, whichis constructed to be mounted upon and secured to the bed or table 42 inthe same manner as are the units 52 and 53, as was described above inconnection with Figure 10, the clamping elements 45fi6 for the powerunit cl being shown in Figure 8; thereby the power unit is adjustablypositionable and quickly alignable with the other units.

Drive head 5| may comprise a built-up housing-like base frame I35 whichmay be given a flat top to support an electric motor I36 (Figures 1 and8) and a reduction gear unit t3? which is driven from the motor I36 bypulleys and drive belts indicated at !38; reduction gear unit is? may beof any suitable construction and may be provided with any suitable meansfor changing the reduction ratio so as to provide for a suitable rangeof selectability of speeds of drive of the correlated live center driveand control devices in the head stock and tail stock control units.

The low-speed output shaft of the reduction gear unit it! emerges at theleft-hand end (Figure 1) and is shown at I39 in Figure 8, and from thatlow-speed shaft driving connections are provided to drive two jackshafts Hi! and I42- which are rotatably supported in parallel relationin the lower part of the housing frame-I35: (Figures 7 and 8), and ofwhich shaft I4! is so supportedand located that its axis is more or lessin line with the axis of shaft 60 of the head stock unit (Figure 2),while shaft M2 is located forwardly of shaft l 41. Shafts I 4! and H52may be mounted and supported in any suitable bearing structures in thebase frame 535., illustratively by combined radial and thrustanti-friction bearings indicated at 143 in Figure 7. The left ends ofthe two shafts overhang the end of the housing frame, as does thereduction gear shaft E39, and by these overhanging ends the three shaftsare suitably geared together as, for example, by means of gears orpinions i ls, MS, and M5, and a toothed belt or toothed chain Ml whichispreferably provided with a takeup or idler roller or pulley 148, whichis eccentrically carried in a bracket part I59 of aplate-like supportl5! which is carried, coaxially with the shaft its (Figure 8.), by thevertical end wall of the gear unit [31, being rotatively adjustable andlocked in adjusted position by clamping screws E52 passing througharcuate slots I53, whereby slack and back-lash in the belt or chain andits gears may be eliminated and the driving connection and relationshipbetween jack shafts M! and M2 maintained invariable. Furthermore, forreasons later pointed out, jack shaft M2, from which certain controlsare to be driven, makes two revolutions for each revolution of jackshaft ll from which the live center CL is to be driven, and in theillustrative drive this ratio is achieved by making the gear Hi5 oftwice the pitch diameter of gear I46.

Jack shaft M! of the drive head 52 is connected at its left end (Figure7) to the right end of head stock shaft 60 in a manner to permit freedomof substantial shift, in all directions, of the shaft 69 parallel toitself and without affecting constancy of angular velocity of shaft 69as the latter is displaced from coaxiality with the jack shaft Ml. Forthis purpose I provide an intermediate shaft 1-56 which is coupled atits ends to the ends of shafts l4! and 66 by universal couplings I57 and558 which may be of any suitable or known con struction andinterrelationship to maintain identity or constancy of the angularvelocities of the driving and driven shafts even though thedisplacements therebetween effect angularities between each and theintermediate shaft 556. Coupling H58 may be secured to shaft 56 (Figure6), as by interfitting it with a hub member act on shaft 60, beingsecured thereto as by screws lei; in similar manner the other couplingi5'i (Figure '7) may be. secured, as by screws E52, to a hub member I53on the end of jack shaft Ml. These hub members are keyed to theirrespective shafts and the entire coupling between the two is devoid ofplay or back-lash. Keyed hub member it is provided with an axiallyextending slot H34 and the rear wall of the base frame it'd has arearwardly projecting horizontally slotted lug or bracket in the slot ofwhich is neatly fitted, and pivoted by pin use, an L-shaped arm or key16! whose free end, when the key is swung into the position shown inFigure '7, neatly enters the slot I64 in hub' :63 and locks the parts,including jack shaft It! and head stock shaft 60, in a correspondingposition against rotation, a position with respect to which other partsmay be adjusted or set, in initially setting up the machine for aparticular blade-grinding job.

Projecting forwardly from the front wall of housing frame is a similarhorizontally slotted lug IBBinwh-ich an L-shapedarm l'i-llis similarlypivotally' mounted, which arm when swung into the position shown inFigure '7 neatly fits into a slot in a collar Ill clamped, adjustably bybolts I12, to the right end of jack shaft I42, whereby for setting-uppurposes the rotary position of the jack shaft and control parts driventhereby may be fixed relative to the jack shaft MI and the head stockshaft 60.

Referring now to Figure 6, head stock control unit 52 and tail stockcontrol unit 53 are respectively provided with horizontal and coaxiallyaligned jack shafts I '55 and I16 carried in suitable anti-frictionbearings ITI, ill for jack shaft I75. and I78, I78 for jack shaft I16,in turn carried and mounted in the respective end walls of therespective housing frames 56 and 51. The adjacent ends of jack shaftsI15 and HE are coupled together by a telescoping coupling structuregenerally indicated at I80 to maintain driving connection throughoutvarious longitudinal or axial spacings between the units '52- and 53lengthwise of the bed or table 42 and constructed, as is laterdescribed, to permit rotary adjustment of one shaft relative to theother. The left end of jack shaft H (Figures 6 and 7), which is inalignment with the right end of drive unit jack shaft I42, is detachablycoupled thereto by a slit sleeve coupling I32 provided with clampingscrews or bolts I83 and with splined or keyed connections with bothshafts I42 and I15, as indicated in broken lines.

The left end wall of housing frame 56 of head stock unit 52 (Figure 6)is bored out and constructed to form a seat for the outer race of ananti-friction bearing I85, the inner race of which is secured to one endof a control cam shaft I86 adjacent the other end of which shaft I85carries and has clamped thereto the inner races of anti-frictionbearings [3? whose outer races are fitted into and suitably secured inthe bore of a large heavy boss 188 that is integrally formed with thebottom of the housing frame 56 and projects upwardly therefrom. Jackshaft I and cam shaft 536 are geared together by gears I9I and I92 of1:1 ratio, the gears being non-rota tively fixed to their respectiveshafts, as by taper pins I93 preferably threaded at their small ends andprovided with draw nuts as indicated. The right end of cam shaft I85closely adjacent the heavy bearing support 8'il88 has secured to it acontrol cam unit, generally indicated by the reference character I96,which is to coact with and control the displacements of the horizontallink 92 and the pendent link 93 supporting the live center shaft 6i); itcomprises two cams LV and LH which, as later described, coast with otherparts to determine, respectively, the vertical and horizontal componentsof displacement of the ball-ended center CL per unit angle of rotarymovement of that center and the workholder W.

Tail stock control unit 52 is similarly provided with a cam shaft andcam unit, being in general constructed right-handed in relation to thelefthanded construction just above described. The right end wall ofhousing frame 5'! (Figure 6) is bored out to support the outer races ofan antifriction bearing I98, the inner race of which is secured on theright end of cam shaft 206, as shown, and near its right end cam shaft2% extends through and has secured thereto the inner races ofanti-friction bearings 2E1 whose outer races are fitted into andsuitably secured in a large bore of a heavy boss 202 integrally formedwith the bottom Wall of the housing frame 51;

and upstanding therefrom, as is also shown in Figure 10, and on theinner end of cam shaft 2%, adjacent the just-described bearing support2o: 2e2, is secured the cam unit generally indicated by the referencecharacter 2% and comprising two cams RV and RE which coact with otherparts to give the ball-ended center CR respective vertical andhorizontal components of displacement or movement per unit angle ofrotary movement of the work-holder W and the blade or blades carriedthereby. Cam shaft the is driven from jack shaft M5 by gears 28% and 2&5of 1:1 ratio and respectively pinned to the shafts by taper pins 206with draw nuts on their smaller ends as shown.

The vertical-component cams LV and RV of the two units, by thejust-described constructions, will be seen to be positioned justunderneath the respective horizontal links 5% and 52 and each in avertical plane that is substantially midway between the end bearingsupports, such as the bearings 7 I-I2 of Figure 9, by which thehorizontal links are pivoted, and of the latter, at that substantiallyvertical plane and just above the axes of the respectively underlyingcam shafts, is provided with a cam follower, preferably in the form of aroller R, to ride along the peripheral cam face as the cam rotates. InFigures 10 and 11 the construc tion and mounting of this roller R isshown in detail for the horizontal link 62, and a description thereofwill suffice for both. Thus the horizontal link has depending from it anintegrally formed boss 2d? which is provided with an arouate recess orbore 298, the axis of curvature of which is parallel to the axis of theunderlying cam shaft, the depending boss 28? being centrally slotted, asat 2 It, in line with the underlying cam RV and to a width greater thanthe thickness of that cam. There are thus formed two axially spacedseats of more than degrees in extent, being open at their lower endsthroughout less than 180 degrees, for the reception of the outer racesof two axially spaced anti-friction bearings 2H and El: whose innerraces are fitted onto the stud-like shaft extensions 2 I3 and 2M of theroller R with which they are coaxial. Securing plates 2E5, secured tothe boss 2%? by screws 2V5, hold the bearing and roller assembly againstshifting axially relative to the boss 25? and the horizontal link fromwhich it depends. The vertical-component cam can thus enter between thespaced bearing members to engage the roller R which is held thereagainstby the weight of the heavy cross-link (S2 or 92) and of the partspivotally carried by it at its free end.

In this manner and by appropriately shaping the left vertical-componentcam LV in relation to the peripheral shape of the right-handverticalcomponent cam RV, the horizontal links 92 and 62 of the twocontrol units may be swung in upand-down direction (see Figure 10) insuch related degrees and/or rates as necessary to tilt the axis of thework-holder and of a blade being ground, in a vertical plane as viewedin Figure l to present any particular line-like portion of the bladesurface in the same horizontal plane of the horizontal grinding line GLof the grinding wheel.

Whil such actions are taking place the centers CL and CR can be givenhorizontal components of displacement so as to provide any desireddeparture from parallelism between the axis of the workholder W and thegrinding line GL as viewed'in Figure 6, by controlling independently ofeach other in any desired corelationship the displacements in horizontaldirections of the pendent links 93 and 63 about the respective axes oftheir pivotal supports from the horizontal links 92 and 62, by therespective actions of the horizontal-component cam LH in the head stockcontrol unit 52 and ofthe horizontal-component cam RI-I of the tailstock control unit #33 on cam followers or rollers 226 and 22l carriedrespectively by the shaft 69 and the sleeve 87 (Figure 6). These rolleror cam followers 228 and 22] are rotatably mounted on shaft 60 andsleeve 8? by anti-friction bearings 222 and 223, respectively, the innerraces abutting against suitable shoulders against which they are clampedand secured by nuts 224 and 225, respectively.

The inner ends of two axially spaced springs 226 and 22'! are anchoredto the lower ends of the arms $3 and 93 of the pendant link 93 (Figure6), and at their forward ends are secured by links 228 to the front wallof the housing frame 56; they are under tension to yieldingly bias thelower end of the pendent link 93 toward the front of the housing frameand thus always maintain the cam follower roller 220 of shaft 60 inengagement with the cam LH.

In like manner two axially spaced springs 239 and 23! have their rearends secured to the lower arms 63 and 63 of the H-shaped pendent link 63with their forward ends anchored by links 228 to the front wall of thehousing frame 51, being tensioned to yieldingly maintain the roller 22]in peripheral engagement with the cam RH. The relationship of theseparts is better shown in the transverse section of Figure 10.

Cam units I96 and 263 (Figure 6) are driven in unison, jack shafts I andHE being connected togetherby the coupling I86; they make one completerevolution for each half-turn of head stock shaft 6!] and thework-holder W where the latter is constructed, as in the illustrativeembodiment, to support two blade members T, T in precise juxtapositionto each other and with their axes O--X coincident with the axis of thework-holder W, whereby an exact 180 degrees of rotation is allocated toeach blade memberv T during which its blade-surface F is shaped (Eigure3) During each such half-turn the cam units W6 and 283 convey to thework-holder W the necessary wobble by giving the ball-ended centers CLand CR the needed interrelated horizontal and vertical componentsofdisplacement which have to vary and change or differ at the two endsof the work-holder axis and in such sequences as is necessary to presentsuccessive straight-line portions of the blade B always and only to thehorizontal grinding line GL of the grinding wheel 22. Accordingly thecontour of the left vertical-component cam LV differs from the contourof the right-hand vertical-component cam RV, and in the same manner thehorizontalcomponent cams LH and RH differ in contour. Companion left andright end cams may have portions geometrically equal Or geometricallysimilar; in the former case the corresponding portion of the bladesurface F would be straight line faired with the elements parallel tothe axis OX (Figure 3), and in the latter case a corresponding portionof the blade surface F would be cut or shaped or ground, also straightline faired, but with the straight line elements divergent and notparallel to the axis OXi' Other portions of the cam peripheries orcontours may have curvatures which geometrically are neither equal norsimilar, and that may be true throughout the entire effective controlportions of all of the cams,- according to the straight line fairedconformation desired for the blade surface F. Any desired similaritiesor dissimilarities, according to need, may be provided in or throughoutvarious companion portions of the right and left cams that control thephysical displacement of the centers CL and CR; for example, one of thecenters may, throughout the desired portion of the rotation of theblade, partake of displacement only horizontally-or only vertically orremain stationary, while the other center is shifted or displaced by itscontrol cams. of the blade face may have to be cylindrical and of thesame radius to the axis O-X throughout, and in such case correspondingportions of the control cams for the two centers are given shapes tohold the two centers against displacement throughout the desired angleof rotation of the blade. Thus a wide range of straight line fairedcurvatures may be cut or ground into the blade surfaces according towhatever relative character-. istics of shape or curvature are given thelines G and H (Figures 3, 4, and 5) along which, as earlier described,the ends of the generating straight line move. Also, it will now beapparent that, within limitations, the grinding wheel 22 may have itssurface shaped or curved, for example, slightly convex, so that thegrinding line GL departs from straight-line relation whereby blade facesmay be shaped having the peculiarities or characteristics in relation tothe blade axis as above described excepting that instead of beingstraight line faired, they are faired according to the curved or othershape given the grinding line GL; in such case the grinding wheel is notaxially reciprocated.

In Figures 16 and 17 are diagrammatically shown relationships of theparts respectively at the commencement of grinding at the leading edge2i! (Figure 8) and the termination of grinding at the trailing edge 2 i,the parts being schematically shown as they would be seen from the leftin Figure 6. Referring first to Figure 16, and assuming that thestraight line terminus of the face F adjacent the leading edge 2%] is tobe parallel to the axis 0-K (Figures 3, 4, and 5), to pre-, sent thatterminus to the straight grinding line GL, the coincident axis O-X ofthe work-holder W and blade or blades T has to be dropped belowthehorizontal plane H--P in which the grinding line GL lies andaccordingly the vertical-component cams LV and RV have portions of equalradius engaged by the two rollers R of the horizontal links 52 and 92dimensioned to lower both ends of the axis OX below the horizontal planeHP to the appropriate extent. Because of that equality at these startingpoints the rollers R, R and the two horizontal links 62 and 92 appearcoincident in Figure 16, as do the corresponding equal portions of thetwo cams. Correspondingly the horizontal-component cams LH and RH, wherethey engage the rollers 22c and 2| I respec-- tively, have portions ofequal radius to displace centers CL and CR horizontally to the sameextent to just bring the above-mentioned surface terminus at the leadingedge 20 into coincidence with the grinding line GL; as indicated inFigure 16, that is a displacement to the left of the vertical plane V- Pthrough the pivotal connections of the pendent links to their respectivehorizontal links. Because of that equality of radius and of horizontaldisplacement of both ends of the axis OX, the pendent arms'63 and By wayof further example, a portion,

19 93 and their respective rollers 22a and 22! appear coincident inFigure 16.

Were the straight line terminus of face F adjacent the leading edge 20to be not parallel to the axis OX (Figures 3, 4, and that terminus wouldbe brought into coincidence with the straight grinding line GL of thegrinding wheel, at the above-mentioned starting points of the cams, byproviding the required inequality of radii, at the starting points, inthe companion vertical-component cams LV and RV or in thehorizontal-component cams LH and RH, or both, according as theout-of-parallelism is only in horizontal projection as viewed in Figure3 or is only in vertical projection as viewed in Figure 3, or is in bothhorizontal and vertical projection.

As the work-holder W slowly rotates counterclockwise (Figure 16),successive companion portions of the horizontal-component cams and ofthe vertical-component cams shift the respective supporting centers CLand CR (Figure 6) and hence the ends of the work-holder axis incorrelation to each other but mechanically independently of each other,giving the axis OX about which the Work-holder W and blade T is swungthe necessary displacement or wobble to present successive linearportions of the blade face F to the horizontal grinding line GL, alwayswithout material or detrimental engagement with the grinding wheelsurface above or below the grinding line GL, until the straight lineterminus at the trailing edge 2| of the face F (Figure 3) is reached. Inthe earlier stages of the rotary movement of the work-holder and blade,commencing at the leading edge (Figures 3, 4, and 5), the companionvertical-component cams LV and RV shift the two supporting centers sothat the axis OX is below the horizontal plane HP through the grindingline GL (Figure 16), while at the same time the horizontal-componentcams LH and RH shift the axis ends in correlation, but because of thepeculiar shape of the blade, during the later stages of this rotarymovement, the vertical-component cams LV and RV shift the centers CL andCR to bring the axis OX of work-holder and blade above the horizontalplane IIP as indicated in Figure 17, where the parts are shown with theend terminus of face F at the trailing edge 2| of the blade exactly atthe grinding line GL. Because that end terminus of the face F is notparallel to the axis OX either in vertical or horizontal projection asviewed in Figures 3, 4, and 5, the two horizontal links 62 and 92 whichdetermine the vertical displacement of the two supporting centers do notappear in coincidence nor do the pendent links or arms 63 and 93 bywhich the horizontal displacement of the supporting centers and the endsof the axis is effected. At this position of the parts where the endterminus of the face at the trailing edge 2| is being ground, the axisOX appears in Figure 17 tilted to both the horizontal plane H--P and thevertical plane V-P in order to bring the straight line terminus of faceF at the trailing edge 2| into coincidence with the straight horizontalgrinding line GL of the grinding wheel; Figure 17 thus illustratesthree-dimensionally though schematically one position of wobble of thework-holder and blade axis O--X, happening to be a position at theconclusion of the cutting or grinding operation.

In between the commencement of the grinding adjacent the leading edge 20and the conclusion of grinding at the trailing edge 2|, the axis OX mayat times be parallel to the grinding line GL and at other times maypartake of angularities, of which one is illustrated in Figure 17,according to the contour required for the blade face F; the angularityof the axis OX relative to the grinding line GL may be at times only inhorizontal projection, at other times only in vertical projection, andat other times in both vertical and. horizontal projection as viewed inFigures 3, 4, and 5. With the illustrative shape of blade shown in thelatter figures, the axis OX, while bodily shifted horizontally andvertically, is maintained parallel to the grinding line GL throughoutthe geometrically equally conformed full-line portions of the cams LVRVand LHRI-I as seen in Figure 16, to grind the earlier above-describedportion F (Figures 4 and 5) of the face F and thereafter the axis OX,while physically displaced horizontally and vertically, as needed, isshifted angularly (made to wobble) with respect to the grinding line GLunder the control of the non-coincident and differently contouredportions shown in full lines and broken lines of the cams LV and RV,respectively, and of the cams LH and RH, respectively, in Figures 16 and17 for effecting the shaping of the portion 1 of the face F as seen inFigures 4 and 5. The transition from one type of shift to the othertakes care also of the difference in the angles a: and :0 abovedescribed in connection with Figures 4 and 5.

The face of the blade B is thus steadily and progressively presentedelement by element always to the horizontal grinding line GL, throughoutwhatever shift, parallel or angular, is given the blade B and its axisOX vertically and horizontally; at each successive increment of rotarymovement or translation of the blade surface relative to the grindingline GL, the grinding wheel cuts the blade face always in a straightline, the succession of straight lines thus cut, for the successiveincrements of rotary movement and corresponding increments of shift ofthe same or different magnitude or direction at the respective ends ofthe axis O--X, merging side by side into each other. The resultantsurface F is smoothly shaped and is curved to the desired contour and,with the grinding line GL straightlined, the resultant contoured face Fof the blade is straight line faired.

The work-holder W continues to rotate, as do the two cam units I96 and203, the work-holder rotating to finish out the degrees of rotarymovement allocated to it for the grinding of one blade B and the two camunits to finish out the 360 degrees of rotary movement thereof allocatedto the 180-degree turn of the work-holder W; the completion of that180-degree turn of the Work-holder W finds the two blades B, Bvertically juxtaposed to each other, the already ground blade B being ata fi-oclock position and the other blade 13 carried by the work-holder Wbeing at a l2-oclock position, as viewed in Figures 16 and 1'7, with theball-ended universallyacting driving dog ||7 (Figures 6, 13, and 14) atthe 6-oclock position. From these positions the parts, continuing torotate, commence a second cycle during which the work-holder W rotates18.0 degrees and the two cam units I96 and 203 rotate 360 degrees toeffect the controls and shifts or wobble above described but now inrelation to the other blade carried by the work-holder, the face F ofwhich is contoured as above described, and with its axis coincident withthe axis of the already ground blade B, the contoured laeemsee "face .ofthe latter is exactly duplicated* in the former.

' As shown in Figures 16 and 17, the respective cams of the two camunits I96 and 233 have conformations which during the rotary transitionof the work-holder from the position shown in Fig ure 17, were thetrailing end terminus of face F is being cut or ground, to a position topresent .the leading edge terminus 23 of the face of the other blade 13to the grinding line GL, shift the axis OX and the work-holder away fromthe grinding line and downwardly; this transitory shift from one cycleto the next not only takes care that the leading edge portion of thesucceed- .ing blade is properly presented to the grinding ..line GL, butalso takes care that the body portion of the work-holderW interveningthe two blades supported by it is prevented from contacting thei'grinding wheel.

' When the face of the second blade B has been ground and the secondblade assumes a 6 oclock position (in Figures 16 and 17), the ball-endedI driving dog II? is at the 12 oclock position, with I the manual screwI23 that 'coacts with it (Figure 14) passing toward the front of themachine. At

this point, the grinding wheel and its slide 3I having been retractedrearwardly (Figure 6), the drive of theheadi stock and tail stockcontrol resultant increase in distance between the two :centers CL andCR, the work-holder with the ground blades is removed and anotherworkholder with two blades therein to be ground is substituted on thecenters for it, driving dog II'I entering the work-holder slot H8 toengage the lock screw I23 (Figure 14) whence the operator turns thescrew I 23 to engage the ball-ended dog H8 to take up play betweenitselfand the companion screw I23.

While the center CR may be axially displaced to the right in Figure 6,by manually opposing the spring I3I for purposes of mounting ordismounting the work-holder, spring I3I :is' relatively powerfulin orderthat it dependably' fol low up toward the live center CL'during wobbleof the work-holder, and accordingly it is preferred to providepower-actuated means for re- ;tracting the center CR. This. preferablycomprises hydraulic means in the form of a cylin- Jder 236, as shown inFigure 6, mounted and secured to the arm I53 of the pendent link 63 incoaxial relation with the frame sleeve 81 carried by the link and thesliding sleeve 6| that carries center CR. One end wall of cylinder 235is providedwith an aperture and sealing ring 231 for the passagetherethrough of a piston rod in the form of a stepped or shoulderedtubular member 233; about its smaller-diametered right-hand end (Figure.6) and abutting against theshoulder therein, .1

hollow'piston rod 238 carries a piston generally indicated by thereference character'240, comprising a collar, two washers between whicha leather or other yieldable piston ring is peripherally clamped, allclamped against the piston rod shouldered by a nut 24! threaded onto theouter end of the hollow piston rod 238. The other end of the latterpasses through the helical spring I3I and is threaded, as at 242, into'the bore of theslidable sleeve 6|. A'washer-244 extends about the hollowpistonr od 238 and bears 'against the yieldable sealing'ring 231 againstwhichitis held by one end of the'spring I3 I. As'the-l'atter acts uponthe slidable sleeve 6| "and center CR as above described, piston 240'andpiston rod 238 slide freely relative to the "cylinder and sealing ring.'Howev'er, upon supplying the 'cylinder chamber-to the left 0f thepiston 240 with fluid under pressure, preferably a liquid, 'the pistonand sleeve and center are I thereby-moved toward the right in oppositionto'spr-ing I3I andmay'be held so displaceduntil the-pressurefluid' is'released from the cylinder. Cylinder '236 provided with a port channel245 which mates-with a channel'in the cylinder head 246 to whichaflexible pipe or conduit 24! may be connected to supply the cylinderchamber with fluid under pressure and to release the same fromthe'cylin- 'der, through a suitable two-way valve 258 connected,respectively, to a fluid supply line2'50 and exhaust line 25I. Valve 248is preferably m'anually operated fromthe front of the machine as, forexample, by ahand lever 252 (Figure "1) s0 thatthe operator can setvalve 248 in one position to connect cylinder to supply line 25il andthereby withdraw center CR and hold it 'withdrawn, while he removes andreplaces the workholder and then set valve 248 in its other position toconnect the cylinder to the exhaust 1ine'25l to let spring I3] enterthecenter CR in'the journal box JR of the work-holder and thereafterlet thespring follow up changes in the projected distance between the centersCL" and'CR as the work-holder W wobbles.

The just-described construction for hydraulically controlling thecenter'CR achievesother advantages. Desirably, under some circumstances,center CR (Figure 6) and sleeve fil are permitted to rotate to eliminatefriction and wear at the ball end '55 of center CR and journal-box JR,the rotation. being slow and beingjefiected in response to the slowrotary movement of the journal box JR. itself; in such case the key maybe omitted from the splined connection 133 earlier above mentioned,whereupon sleeve BI is not only slidable but also rotatable relative 'tothe spaced bearings I21, I28.

'Drainageof liquid that might leak'or emerge from cylinder 238 at thesealing ring 231 is easily effected by a channel 253 that connects withthe interior of sleeve arm (i3 and extends in the wall of cylinder 233,leading at its right-hand endto a mating channel and pipe connection 254in the cylinder head 246.

Cylinder head 245 has an opening 255-aligned with the axis of the hollowpiston rod 238 so that a rod'may be slid therethrough for dislodging thetaper center CR from its taper seat in the sleeve '6 I, when it isnecessary to replace the center, for

example, with a differently dimensioned one.

Live center CL in the head stock may be dislodged from its taper seatinthe shaft'tfl by means of'a nut 256 threaded onto its outer end andwhichwhen turned to bear against the end of shaft'60,

acts to unseatand withdraw the center CL.

true of the two horizontal-component cams LH and RH; moreover, camdimensions and the justmentioned contours may in turn vary considerablyaccording as it is required to grind differently dimensioned orcontoured blade faces under controlled conditions of wobble ofwork-holder and blade members relative to the fixed grinding line GL.All four cams bear the proper relation one to the other, and if thatrelationship is established for any selected point in a single grindingcycle, it remains proper and so established for all other points in thecycle.

Accordingly the two cams LV and LH (Figure 6) of cam unit !95 of thehead stock control unit 52 can be and are constructed as separate cams,each with its particular contour to give, respectively, the requiredvertical-components of displacement and horizontal components;preferably they are made to be capable of relative rotary adjustment tofix their relation to one another, a relation which, because of the90-degree displacement of their respective roller followers, should alsobe a 90-degree displacement between them. Thus cam LI-I on cam unit 595has a sleeve-like hub 26!! which is internally tapered to fit onto thetapered end of shaft I86 to which it is splined or keyed as at 252. Hub26%! is externally cylindrical to receive thereon cam LV and itssleeve-like hub 26! with a face of cam LV abutting against the end ofhub 25%! of cam LI-I. Cam LV has a number of arcuate slots through whichextend screws 263 that are threaded into hub 26!! whereby cam LV may berotatively adjusted relative to earn Ll-I to give the desired QO-degreedisplacement and then secured by tightening the screws 263. Graduations,indicated in Figure 6, on hub 26! may be used to facilitate setting. Theresultant cam unit is clamped to cam shaft !86 by clamping plate 265 andclamping screw 266 threaded into the shaft and it may be so secured inany selected rotative relation to the shaft itself, without disturbingthe relation between the two cams LV and LH.

The two right-hand cams RH and RV of the tail stock control unit arealso constructed as individual cams and respectively appropriatelycontoured, but are assembled to each other in a manner to permit settingof one about the axis of the other. Thus horizontal-component cam RH hasan internally tapered hub 276 to fit onto the tapered end of cam shaft290 (Figure 6) and provided with a keyway as shown to coact with a key212 in the cam shaft whereby the cam is assembled to the cam shaft 2% infixed relation; the hub 218 is externally cylindrical to receive thevertical-component cam RV and its hub 21! which terminates against aface of cam RH to which it is secured by clamping screws 213 (Figures 6and 10), illustratively four in number, which pass through arcuate slots215 in cam RH, whereby cam RV is rotatively adjustable relative to camRH throughout a suitable range in either direction from a true QO-degreedisplacement between the start-grinding points of the two cams. Asindicated in Figure 6, hub 21! on adjustable cam RV may bear graduationsor other indicia relative to a marked point or datum line on the face ofcam RH to indicate direction and extent of departure from the juststated90-degree relation. The resultant twocam unit 203 is clamped to camshaft 200 by clamping plate 215 and clamping screw 21B threaded into thetapered end of shaft 200.

As seen in Figure 6, each cam shaft I86 and 200 has a brake drum 211,218 and each has thereabout a suitably lined adjustable brake band 280comprising in effect a split metal band having its ends adjustablysecured together by an adjusting screw 28! (Figure 10) and provided withan arm 282 that abuts against the bottom wall of the housing frame.These brakes impose a drag or load on the two cam shafts the magnitudeof which is adjustable by appropriately setting the adjusting screws 28!and thereby back-lash and play in the drives to the respective cams isalways taken up and is prevented from causing divergence in back-lash orplay from throwing the two cam units I96 and 203 out of synchronism;they can also aid in initially setting the cam units in relation to eachother.

With cam unit I96 at the left, fixed to cam shaft I86 and therelationship between the two cams LV and LH fixed by assembly of the twoas above described, and with cam RH at the right secured in fixedrelation to the cam shaft 200, the desired synchronization of cams RHand RV in relation to cams LH and LV may be readily accomplished by theabove-described structural features. The jack shafts H5 and H6 arecoupled together by a coupling generally mentioned above and identifiedat I in Figure 6; it is constructed to permit rotative or angular shiftof one jack shaft relative to the other for cam adjustment orsynchronization and may comprise a sleeve 290 keyed and secured to theright end of jack shaft M5 to receive in its outer end a companionsleeve 29! in which the left end H6 of jack shaft HE is telescopicallyreceived, the jack shaft portion lit and the aperture in sleeve 29!being of any suitable non-circular cross-section so that they cannotrotate relatively to each other and hence sleeve 29! can drive jackshaft ilk-I16 The telescopic relation between sleeve 29! and jack shaftpart H6 permits maintenance of the driving connection for differentaxial spacings of the head stock and tail stock units 52, 53 lengthwiseof the machine table 42.

The two sleeves 290, 29! are constructed for relative adjustment of theone about the axis of the other, and this means may comprise two opposedaligned screws 292, 293 threaded into two opposed holes in the sleeve290 and that extend along a, chord so that their inner ends project inspaced relation into the cylindrical interior of the sleeve 2%; internalsleeve 29! is cut away or recessed on opposite sides to receive theinner ends of these screws and to leave a portion extending between thescrew ends, forming in effect a radially projecting lug or lever armwhich is clamped between the screws 292, 293. By this means interiorsleeve 29! and hence jack shaft I76 may be adjustably positionedrotatively about the axis of sleeve 299 and jack shaft !15 within a,suitable range or angle of adjustment, and thus cam shaft 290 in thetail stock control unit rotatively adjusted relative to cam shaft !86 inthe head stock unit. With cam RH in the tail stock keyed to earn shaft200, a corresponding adjustment thereof relative to earn LE on the camshaft I86 can be effected to synchronize their settings and theirrespective control actions of their respective cam followers 22! and 220so that the horizontal components of displacement at the respective endsof the work-holder W, whatever their similarities or differences, takeplace synchronously. Vertical-component cam RV in the tail stock, bymeans of the screws 213 and slots 214 in the fixed cam RH may be set ineither direction about its axis and hence in relation to the setting ofcam LV in the head stock unit so that? the two are set-and act syn-.

chronously and so that-the intended and desired vertical components ofdisplacement of the two ends ofthe work-holder axis, whatevertheirsimilarities or differences, take place synchronously.- Thus the partsmay be readily set to achieve the'required displacement or wobble of theaxis of the Work-hclder and blade to give the latter its peculiarsurface shape. and readjustment facilitated.

For purposes of assembly and cam setting, provision is made for readilypositioning and holding cam followers and related parts out of coactingrelation with the respective cams. Thus each of the springs 226, 221 inthe head stock (Figure 6) and'springs 3E1,- 23I inthe tail stock may bequickly released so as to free the respective pendent arms 93 and 53upon which they act. Each end link 223 is constructed as is better shownin Figure 10 and comprises two parts 228 and 228 ofrectangularcross-section and hingedlyconnected together by a pin 28 i-whereby theouter part 228 provided at its outer end with a cross-- bar handle 285,may be manually swung into or out of alignment with the part 228 towhich the spring end is hooked; The front wall of the housing frame hasa hole 286 externally surrounded by a boss 28? against which the outerlink part 228' rests when swung at about 90 degrees to the inner linkpart 228 thus holding the spring under tension; but when outer link part22B is swung into alignment with inner link part 228 the now alignedlinks can slide together, to the left in Figure 10, along the hole 235to an extent limited by the engagement of cross-bar handle 285 with theboss 281. Thereby the tension of the spring is relieved. In this mannereither or both of the pendent arms 63 and 93 can be freed from thespring tension and cam'follower rollers 220 and 22I (Figure 6) releasedfromenforced engagement with their respective cams LH and RH.

Each of the horizontal links G2 and 63, with the above-mentioned springreleased, may now be freely lifted up manually, cover plates 58 and(Figure l) of the head stock and tail stock units having been removed,thus to disengage the cam rollers R. from their respectivevertical-component cams RV and LV. These parts being relativelyheavy,,provision is made for facilitating raising them and forselectively positioning each in. upwardly retracted position. Themeans.employed to act on the horizontal links I52 and 92 are the. same, anditwill suffice to describe one of them.

in detail, as is better shown in Figures 9 and 10 with respect to thehorizontal link t2. remote from where it is pivoted has a brackets likeextension 285 east or formed integrally with? it and it is slotted, asat 231, to provide spaced arms between which is loosely received: asquare nut 238 (Figure 10). Nut 298 is mounted in the slot 29? forpivoting about an axis parallel to the axis about which the horizontallink itself can pivot at its forward end, as by. two pins 398 Its endi26? I the pins Sill! for the nut 298. When it is desired-r: toretract/either arm I52-or S2 upwardlyyacapi screw 3% (Figure 10).isslid.down throughthe: hole 395 in frame-carried block 3Il3"and"then':threaded into the threaded hole in the link-- carried nut 298, :thepivotal mountings of block and nut permitting these-parts to'beself-'align-. ing under the action of screw 3% for this pur-f pose aswell as during the subsequent changes in angularity of the axis of screw3% 'i'elative'to the horizontal link itself as the latter is retractedupwardly. Upward retraction may be'efiected toanydesiredextent'according to the extent of threading of screw'act'intonut 298; by using a wrenehon the screw tdfigsuch upward retractionof the horizontallink and the pendent" link carried by it isaccomplished'with ease. Thusiu. the cam follower roller B. may be easilyretracted from its position of coaction with the-verticalcomponent' camin either the head stock unitor 1 the tail stock unit, or'both. Thecam'units I96 and-2st (Figure 6) are'thus clear for replacement or adjustment;

Another aid in setting up the machine or in: making adjustmentscomprises a dog arm. I61 (Figure 7) by which head stock spindle 60 maybe locked always in' a single at-restposition;-. by swinging the dogarmifi'l to enter the slot I64- (Figure?) in the hub I63; thereby,':inthe illustrative embodiment; freezing the iball-ended:--* spindle drivedog Ill and the work-holder W in'l the, position shown in Figures 6 andl6wherein that geometric element of one of the two blades in thework-holder that correspondsto a sur-- face line element through theverticalaxes shown Figures and'5 is presented at the!) oclockz positionand in juxtaposition to the grinding wheel '7 grinding line GL. With theparts thus frozeniin: position, left-hand cam unit I 96 comprising cams:LV and LH may be securedito cam shaft l86l(Fig-;; ure 6) and right-handcam unit QUBcomprising" cams RV and RH secured to cam shaft 200, by therespective keys: 262' and 212; the key slots .or locations in thecamshafts I88 and ZQG'andthei keyways in the respective cams LI-Iand RH areso located that, with the keys ZiiZ'and 212' aligned* with each other orat'the same oclock position as. x viewed' from one end of Figure 6, thecams. LH and RH are correspondingly aligned and syn= chronized, arelationship'which in turn'is fixed by the geared-connections of the camshafts: I86 and 2% tothe respective jack. shafts H5 and: I16 1 and whichcan be precisely determined by 3131-) propriately setting therelationship between the. telescoping coupling sleeves'29il, 29l(Figure.i6)"as:- above described; With the toothed belt Isl-(Fig ures'?and 8) removed ordisengaged from gear-J M5 or. gear M5, or both, andwith jack'shaft I i'I (Figure 7) locked by the lock arm. I61, coupled;together jack shafts M2; I'l5;'and 116 may now be manually rotated to;bring the'cams LH and RI-Iyeither empirically ,or by appropriatemarkJ-Ii ings on the cams, to a rotary position that gives:- therespective horizontal components of displacement' appropriate for theabove-mentioned 9 oolock position of the: above illustratively. se-ilected. surface line element of the blade to be ground. With. theillustrative formof'bladeB diagrammatically indicated in Figures 3, 4,and 5, it happens that, at that position,the pendent armsfit and 53' areexactly vertical. Collar I'H on jack. shaft M2 (Figure 7) is now set andclamped to shaft M2 in position to receive dog.

arm Ht which is swung into the slot'ofthe col-- lar, thus freezing therotary position of the cou-:

